As some of you know, I recently bought a celsior with a blown air shock. Well, today after a few hours of hard labor I managed to replace the blown shock with a used one. The car still sits low, so I thought this one was also blown, but I drove the car and it feels 90%better than it used to with the other shock. The guy that sold me the car told me that when the shock blew, the TRC light came on and that he couldn't adjust the height anymore, so the front sits higher and the rear way low. The thing is that the shock that I just installed works, but the TRC light still on and the height of the front and rear are still the same.
The question is:

What could be the problem here?

There's an ecu in the trunk that's soley for the air suspension, so I was wondering if it could be that. The good news is that I have a spare in case someone tells me or thinks it could be that. This car is new to me, so I wouldn't know.

Thanks for the help!